API gravity

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A convenient scale of the American Petroleum Institute (APIAmerican Petroleum Institute) that is inversely related to the density of liquid petroleum: APIAmerican Petroleum Institute gravity = (141.5°/[secific gravity at 16°C]-131.5°). A higher APIAmerican Petroleum Institute indicates lighter oil. Fresh water has a gravity of 10° APIAmerican Petroleum Institute. Heavy oils have less than 25° APIAmerican Petroleum Institute, medium oils have 25 to 35° APIAmerican Petroleum Institute, light oils have 35 to 45° APIAmerican Petroleum Institute, and condensates have more than 45° APIAmerican Petroleum Institute.[1]

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  1. Peters, Kenneth E., David J. Curry, and Marek Kacewicz, 2012, An overview of basin and petroleum system modeling: Definitions and concepts, in Peters, Kenneth E., David J. Curry, and Marek Kacewicz, eds., Basin modeling: New horizons in research and applications: AAPG Hedberg Series no. 4, p. 1-16.